To make the lemon poppy seed cake:

• Preheat the oven to 350°F. Spray a 9×5″ loaf pan with baking spray and line with parchment paper, allowing excess paper to hang over the sides, creating a “sling” that you will use to lift the cake out of the pan after it’s baked.
• In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium-high speed until light and fluffy, about 4 to 5 minutes, stopping halfway through to scrape down the sides of the bowl and again at the end.
• Mix in the eggs, one at a time, beating each on medium speed for 20 seconds before adding the next. Add the vanilla extract, lemon extract (if using), and lemon zest, and mix to combine.
• In a separate bowl whisk together the flour, baking soda, baking powder, kosher salt, and poppy seeds. In another bowl, whisk together the sour cream, buttermilk, and lemon juice until smooth.
• Alternate adding the flour mixture and the sour cream mixture to the batter, beginning and ending with the flour mixture, mixing on low speed after each addition until the ingredients are just incorporated. Be careful not to overmix. Next, use a rubber spatula to gently scrape down the sides of the bowl and fold the batter a few times to ensure that all the ingredients are incorporated.
• Pour the batter into the prepared pan and gently smooth into an even layer. Tap the pan on the counter a few times to release any air bubbles. Bake until a toothpick inserted in the center of the cake comes out clean, 45 to 50 minutes.
• Allow the cake to cool in the pan for 5 to 10 minutes, then use the parchment paper handles to lift the cake from the pan and place on a wire rack set over a baking sheet lined with parchment paper. While the cake is cooling in the pan, prepare the lemon glaze.

To make the lemon glaze:

• Place the sugar and lemon juice in a small saucepan set over medium-low heat, stirring frequently, until slightly thickened and the sugar is dissolved.
• Generously brush the warm glaze all over the warm cake, making sure to coat the top and all sides of the cake. Do this twice more, giving you a total of 3 coats of glaze (it’s okay if you have some glaze leftover).
• Allow the cake to cool completely before topping with the lemon icing.

To make the lemon icing:

• In a small bowl, whisk together the powdered sugar and 2 tablespoons lemon juice, until a thick, pourable icing forms. If necessary, add more lemon juice, one teaspoon at a time, until you’ve reached the right consistency.
• Pour the icing over the top of the cooled cake, allowing the icing to drip down the sides.